Telephone does not ring when configuring it in user interface

When you configure a telephone under "Telephony > Telephony Devices > Configure New Device" in the user interface, during the procedure the FRITZ!Box checks whether the telephone is correctly connected. After you select the port the telephone is connected to, the question "Is the telephone ringing?" appears. However, the telephone does not ring and you cannot continue with the configuration.

Simply proceed as described below. After each measure, check whether the issue persists.

1 Connecting the telephone directly to the FRITZ!Box

The following steps are only necessary if the telephone is connected to a PBX that is connected to the FRITZ!Box:

Disconnect the telephone from the PBX and connect it directly to the FRITZ!Box.

If the telephone now rings, then the PBX is incorrectly configured. The manufacturer can provide you with instructions on configuring the PBX.

2 Connecting and configuring an ISDN telephone

Entering your telephone numbers in the ISDN telephone

Delete all of the numbers configured in the telephone.

Re-enter the desired numbers in the telephone exactly the way they are displayed in the FRITZ!Box user interface in the settings for the telephone on the "FON S0" tab.

Note:You can find information on configuring the telephone numbers (MSNs) in the telephone's manual, or consult its manufacturer directly.

Connecting a single ISDN telephone

Disconnect all devices (such as telephones, PBXs, faxes) and cables from the "FON S0" port.

Connect a single telephone to the "FON S0" port. Do not connect the telephone to the FRITZ!Box by means of a PBX or an ISDN hub.

Check whether you can now make calls with the ISDN telephone.

If you cannot make outgoing calls:

Proceed with the following section. Do not connect any further telephony devices yet.

If you can make calls, then another device or its cable is defective, or a device is incorrectly configured (for example incorrect telephone numbers, dialing rules). To find out which device was causing the issue:

Connect the other ISDN devices again. Do not connect more than one ISDN device without its own power supply to the "FON S0" port.

If the error occurs again after you connect a particular ISDN device, then the device or its cable is defective.

If the error occurs again after you connect a PBX, then the PBX is either defective or incorrectly configured, for example incorrect telephone numbers, incorrect dialing rules, or dial around services.

3 Testing a different telephone

Disconnect the telephone from the FRITZ!Box and connect a different telephone to the same port.

Important:The ISDN telephones you connect to the FRITZ!Box must be suitable for use with ISDN point-to-point connections. Furthermore, the cables of ISDN telephones may not exceed 10 m. ISDN point-to-multipoint lines are common in the private sector and in small offices, whereas ISDN point-to-point connections tend to be used in professional environments.

If the second telephone rings, then the first telephone or its cable is defective.